Titelbaum, Jenna R.

ABSTRACT Purpose To validate a custom smartphone application for at‐home visual acuity (VA) measurement in children. Methods A total of 452 children aged 3–17.5 years participated. Certified examiners measured in‐office test–retest VA (logMAR) using gold‐standard Amblyopia Treatment Study HOTV (3‐to‐6‐year‐olds, younger cohort) or electronic Early Treatment of Diabetic Retinopathy Study (7‐to‐17.5‐year‐olds, older cohort) protocols at 3–4.5 m and app‐based VA at 1.5 m. Caregivers measured at‐home app‐based VA at 1.5 m. Results Comparing at‐home app‐based with gold‐standard VA, in eyes 20/40 or better, 95% (143/151) and 93% (91/98) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = −0.03, older = −0.04; 95% limits‐of‐agreement half‐width (LOA): younger = ±0.26, older = ±0.22). In eyes 20/50 or worse, 66% (42/64) and 75% (76/101) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = 0.11, older = 0.13, LOA: younger = ±0.50, older = ±0.51). Comparing in‐office app‐based VA with gold‐standard VA, in eyes 20/40 or better, 98% (160/164) and 94% (99/105) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = −0.03, older = −0.03; LOA: younger = ±0.22; older = ±0.24). In eyes 20/50 or worse, 85% (60/71) and 91% (101/111) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = 0.04; older = 0.04; LOA: younger = ±0.39; older = ±0.24). For gold‐standard test–retest, in eyes 20/40 or better, 99% (163/164) and 99% (104/105) of the younger and older cohorts had retest within 2 lines, respectively (mean differences: younger = 0.00; older = 0.01; LOA: younger = ±0.17; older = ±0.11). For 20/50 or worse, 92% (66/72) and 100% (111/111) in the younger and older cohorts were within 2 lines, respectively (mean differences: younger = 0.01; older = 0.02; LOA: younger = ±0.35; older = ±0.15). Conclusions Our app demonstrated good concordance with the gold standard at home and in the office for eyes with VA of 20/40 or better. However, concordance decreased considerably for eyes with VA 20/50 or worse, particularly at home.

SIGNIFICANCE This pilot randomized trial, the first to evaluate a specific base‐in relieving prism treatment strategy for childhood intermittent exotropia, did not support proceeding to a full‐scale clinical trial. Defining and measuring prism adaptation in children with intermittent exotropia are challenging and need further study. PURPOSE This study aimed to determine whether to proceed to a full‐scale trial of relieving base‐in prism spectacles versus refractive correction alone for children with intermittent exotropia. METHODS Children 3 years old to those younger than 13 years with distance intermittent exotropia control score of ≥2 points on the Intermittent Exotropia Office Control Scale (Strabismus 2006;14:147–150; 0 [phoria] to 5 [constant]), ≥1 episode of spontaneous exotropia, and 16 to 35∆ by prism‐and‐alternate‐cover test, who did not fully prism adapt on a 30‐minute in‐office prism‐adaptation test were randomized to base‐in relieving prism (40% of the larger of distance and near exodeviations) or nonprism spectacles for 8 weeks. A priori criteria to conduct a full‐scale trial were defined for the adjusted treatment group difference in mean distance control: “proceed” (≥0.75 points favoring prism), “uncertain” (>0 to <0.75 points favoring prism), or “do not proceed” (≥0 points favoring nonprism). RESULTS Fifty‐seven children (mean age, 6.6 ± 2.2 years; mean baseline distance control, 3.5 points) received prism (n = 28) or nonprism (n = 29) spectacles. At 8 weeks, mean control values were 3.6 and 3.3 points in prism (n = 25) and nonprism (n = 25) groups, respectively, with an adjusted difference of 0.3 points (95% confidence interval, −0.5 to 1.1 points) favoring nonprism (meeting our a priori “do not proceed” criterion). CONCLUSIONS Base‐in prism spectacles, equal to 40% of the larger of the exodeviations at distance or near, worn for 8 weeks by 3‐ to 12‐year‐old children with intermittent exotropia did not yield better distance control than refractive correction alone, with the confidence interval indicating that a favorable effect of 0.75 points or larger is unlikely. There was insufficient evidence to warrant a full‐scale randomized trial.